Kinetochore Specification and Function

项目总结 在细胞分裂过程中对复制基因组的准确分割对于ALL的正常发育是至关重要的 有机体。染色体分离错误导致非整倍体，这是癌症的一个标志，也是癌症的共同起源 先天缺陷。染色体分离机制也是癌症治疗和治疗的重要靶点。 在许多癌症中观察到的染色体错别率升高与治疗有关。 抵抗。因此，阐明确保染色体准确分离的机制有可能 有助于了解癌症的起源，并指导新的治疗策略的发展。一个 染色体分离的核心是着丝粒，这是在有丝分裂上组装的机器 染色体与纺锤体微管连接。此界面的机制与 调节动粒微管附着体强度的调节机制，正确的附着体 错误，并阻止细胞周期进展，直到所有的染色体都连接到纺锤体。机械和 Knl1复合体/Mis12复合体/Ndc80保守的Knl1复合体/Mis12复合体协调着动粒的调节功能 复合(KMN)蛋白质网络。虽然在表征激酶方面取得了实质性的进展，但 控制染色体分离的机械和调节方面，了解保守的 与动粒定位的磷酸酶相反，蛋白磷酸酶1(PP1c)的表达相对滞后。目标1和目标2 通过定义控制动粒定位、活性和底物的机制来解决这一差距 PP1c的特异性，除了确定动粒对接的PP1c如何控制后期开始和 调节微管连接。为了确保准确的染色体分离，染色体必须实现 纺锤体上的双向，姐妹染色单体完全连接到相反的纺锤体的状态 电线杆。被广泛研究的通路，如纺锤体检查点和极光激酶的纠错作用 确保双向。我们定义了一条在双向后采取行动的路径，以确保通过 稳定定向正确的动粒-微管附着体。目标2还侧重于理解 这一途径的机制基础，涉及保守的定域动粒之间的协调 微管结合Ndc80和Ska复合体及PP1c对其配位的电位调节。最后， AIM 3追求两个新的方向，这两个方向是我们在多细胞遗传模型工作中出现的。第一个是 基于我们的发现，KMN网络在神经形成中具有重要的非有丝分裂作用 系统在胚胎发育过程中。第二个是基于我们令人惊讶的发现，关键的有机体 保守的纺锤体检查点组件的功能是有丝分裂进入的动粒非依赖性促进 生殖系。在这个最终目标中提出的工作将定义井的新的和意想不到的生物功能。 研究了染色体分离机制，并有可能影响针对 针对癌症的这种机器的治疗靶点。

PROJECT SUMMARY Accurate partitioning of the replicated genome during cell division is essential for the normal development of all organisms. Chromosome segregation errors lead to aneuploidy, a hallmark of cancer and a common origin of birth defects. The chromosome segregation machinery is also an important target in cancer therapy and elevated rates of chromosome missegregation, observed in many cancers, are associated with therapeutic resistance. Thus, elucidating the mechanisms ensuring accurate chromosome segregation has the potential to contribute to understanding the genesis of cancer and guide the development of new therapeutic strategies. A central player in chromosome segregation is the kinetochore, the machine that assembles on mitotic chromosomes to interface with spindle microtubules. The mechanics of this interface are integrated with regulatory mechanisms that modulate the strength of kinetochore-microtubule attachments, correct attachment errors, and prevent cell cycle progression until all chromosomes are connected to the spindle. Mechanical and regulatory functions are coordinated at the kinetochore by the conserved Knl1 complex/Mis12 complex /Ndc80 complex (KMN) protein network. While substantial progress has been made in characterizing the kinases that control the mechanical and regulatory aspects of chromosome segregation, understanding of the conserved opposing kinetochore-localized phosphatase, protein phosphatase 1 (PP1c) has lagged behind. Aims 1 and 2 address this gap by defining the mechanisms that control kinetochore localization, activity and substrate specificity of PP1c, in addition to determining how kinetochore-docked PP1c controls anaphase onset and regulates microtubule attachments. To ensure accurate chromosome segregation, chromosomes must achieve bi-orientation on the spindle, the state in which sister chromatids are exclusively connected to opposite spindle poles. Widely studied pathways such as the spindle checkpoint and error correction by Aurora kinases act to ensure bi-orientation. We defined a pathway that acts after bi-orientation to ensure accurate segregation by stabilizing properly oriented kinetochore-microtubule attachments. Aim 2 also focuses on understanding the mechanistic basis of this pathway, which involves coordination between the conserved kinetochore-localized microtubule-binding Ndc80 and Ska complexes and potential regulation of their coordination by PP1c. Finally, Aim 3 pursues two new directions that emerged from our working in a multicellular genetic model. The first is based on our discovery that the KMN network has an important non-mitotic role in formation of the nervous system during embryogenesis. The second is based on our surprising finding that the critical organismal function of conserved spindle checkpoint components is kinetochore-independent promotion of mitotic entry in the germline. The work proposed in this final aim will define new and unexpected biological functions for well- studied chromosome segregation machinery and has the potential to influence strategies directed at therapeutic targeting of this machinery in cancer.